Amazon is doubling down on its Alexa-powered devices, with plans to release at least 8 new voice-controlled hardware devices before the end of the year, CNBC has learned.

The devices include, among others, a microwave oven, an amplifier, a receiver, a subwoofer, and an in-car gadget, people familiar with the matter said. All of the devices will be Alexa-enabled, meaning they can easily connect to the voice assistant. Some of the devices will also have Alexa built in.

Amazon is expected to reveal some of these devices at an event later this month, according to an internal document describing the plans.

The new devices reflect Amazon's ambition to make its Alexa voice technology ubiquitous by focusing on areas where people spend most of their time — at home and in the car. Alexa was initially considered a geeky experiment at Amazon. Now it is now one of the most popular voice assistants, leading the growth of the burgeoning smart speaker market, which is expected to be worth $30 billion by 2024, according to Global Market Insights.

Focus on the home

It's unclear how commercially successful the new devices will be. Amazon has often taken a scattershot approach to its hardware initiatives, releasing not only massively successful products like the Echo home devices, but also experimental projects like Echo Buttons, a light-up device designed for gaming.

But the move signifies Amazon's heavy interest in the connected home. The amplifier, for example, can be used as the central audio panel to control multiple speakers that are set up across the home. The microwave can make Alexa a key part of the kitchen.

Earlier this year, Amazon acquired the smart doorbell maker Ring, which also makes devices that are compatible with Alexa. The company is reported to be working on a secretive home robot, as well, according to Bloomberg.

Having its own home appliances also opens up a new sales channel for Amazon. By partnering with smart home installation companies, Amazon can make its Alexa-powered devices more readily available in new homes. Sonos, for example, has a similar business model, as it said in its quarterly filing that it relies on "custom installers of home audio systems for a significant portion of our sale."

Amazon doesn't disclose sales numbers for the Echo, but has previously said "tens of millions" of Alexa-enabled devices sold worldwide. And in its most recent earnings report, Amazon CEO Jeff Bezos hinted at his ambition for making Alexa more widely used.

"We want customers to be able to use Alexa wherever they are," Bezos said in a statement in July. "There are now tens of thousands of developers across more than 150 countries building new devices using the Alexa Voice Service, and the number of Alexa-enabled devices has more than tripled in the past year."